Baseball Statistics 101

Why Have Stats?

Once upon a time there were two guys who liked to go to the local ballpark and watch the games. Both of them had a different favorite player. They were always jabbering back-and-forth about whose favorite player was better.

“Your guy might get on base more than mine does, but my favorite player hits more home runs,” said the first guy.

“Well,” responded the other, “your guy might hit more home runs, but mine is a better defensive player than yours.”

They would argue, day after day, which player was better. Until one day in the middle of winter, they had an idea. “We will go to the ballpark every day next summer and count how many hits each player has, and how many home runs, and how many runs they score. At the end of the season, we will truly know who is the better player.”

This is not how it really happened, how baseball statistics were invented, but the essence of the story is true: Statistics are about answering questions. Who had more hits? is very different than who is the better hitter? What weaknesses does this pitcher have? Does he walk more hitters compared to that other pitcher? What are the chances the first pitch he throws me will be a strike?

Ten people could watch a team play every game for the whole season and come up with ten different answers to who the best hitter is. But who had the most hits, we can determine that simply by counting. The catch is, the guy with the most hits is not always the best hitter.

Nobody is able to watch and remember every play of every game and remember what happened, so we decided to start counting things. Add, subtract, multiply, and divide those things in different orders and you have got our best attempts at figuring out who is good, who is bad, and who do I want on my team? And every baseball fan uses one stat or another to formulate their answers.

What Did He Say?

If you are just getting into baseball, things can get overwhelming. You cannot watch a half-inning of a ballgame on TV without someone throwing out some numbers, and it can be frustrating if you do not know what they mean. So let’s start with the most widely-referenced stats you will see in the newspaper, on TV, or most websites.

Hitting stats

The simplest thing we can do is start counting things a player does day in and day out: number of hits, number of strikeouts, walks, times hit by a pitch, times put out. Go to a place like, we’ve got a whole bunch of stats across the top. In most cases it will be what he has done this season, although many sites will let you look at different situations: what his stats over his career, against right-handed pitchers, during day games, or even how he has done when the count is 2-0.

Here’s what you will usually see:

G – Number of games played in
AB – Number of at-bats
R – Number of runs scored
H – Number of hits
2B – Number of doubles
3B – Number of triples
HR – Number of home runs
RBI – Number of runs batted in
BB – Times walked
SO – Times struck out
SB – Number of stolen bases
CS – Number of times caught stealing

In 2012, we see that Miguel Cabrera played in 161 games, but Mike Trout only played in 139. So even though Cabrera had 23 more hits than Trout, because he played in 22 more games is it really fair to automatically say he is was a better hitter? Most agree it is not. So we have two stats called Batting Average (AVG) and On Base Percentage (OBP), that allow for a more accurate comparison.

Batting average was much more popular than on-base percentage for many years, but on OBP has increased in popularity a lot over the last few years for a few reasons.

Not all hits are equal though. You would prefer to hit a home run over a single, but AVG and OBP count all hits equally. So how can we give proper credit to the guys with more power? With Slugging Percentage (SLG) and On Base Plus Slugging (OPS).

You could probably call these stats—Batting Average, On Base Percentage, Slugging Percentage, and On Base Plus Slugging—the Big Four of Mainstream Baseball Stats. Know them along with what the simple day in and day out stats and the things that most announcers on television are saying will make sense to you.


Pitching stats have some similarities and some differences with hitting stats. We’ve got our ‘counted’ pitching stats too. The pitching equivalent to ‘at-bats’ is ‘batters faced,’ which is the number of different hitters a pitcher has pitched against, but rather than basing pitcher stats off batters faced like batting average is based on at bats, many of pitching stats are ‘per inning’ or ‘per nine innings.’

Here’s our simple counted stats for pitchers:

IP – Number of innings pitched
H – Number of hits given up
R – Number of runs allowed
ER – Number of earned runs given up
BB – Number of batters walked
SO or K – Number of batters struck out

For starting pitchers you will probably hear winloss record and Earned Run Average (ERA) as the most-referenced stats. For closers, it will be ERA and saves or holds rather than win-loss record.

As previously mentioned you will also see many ‘per nine inning’ stats, like ERA. Others would include BB/9 (walks per nine innings) and K/9 (strikeouts per nine innings). This is similar to how AVG or OBP puts everyone, regardless of how many innings they have pitched, on an even playing field.

One last pitching stat to mention is WHIP, which stands for ‘Walks and Hits per Inning Pitched.’ As a pitcher, you want to avoid allowing guys on base and therefore the fewer walks and hits you allow, the better.

And that about sums it up. If you understand what all the stats we’ve mentioned, you should have no trouble understanding a game on television or the two guys talking in the row behind you at the ballpark. You might even be able to explain a thing or two to them now.

Just remember those two guys from the intro, often times we’ll compare stats from two different players and want to say, ‘It’s obvious this guy is better than that one! His batting average is higher, he’s got more RBIs, and he hit more home runs!’ But always keep in mind what exactly those numbers are telling you: There is nothing in there about how well they play defense, how often they draw walks, or their talent on the base paths. Things have been changing, but some widely used stats are still questionable.

Further reading

Different stats have been developed over the last hundred years or so. But over the last few decades, computers and the internet have allowed people to do studies that would have been impossible in the early days of the game. This has brought about many new theories and stats—some of which have disproven long-held beliefs about the game. You can enjoy baseball a great deal knowing only the stats above, but you might enjoy it even more with knowledge of some of so called ‘advanced statistics’ behind the sabermetric movement.

FanGraphs has a fantastic reference guide for these stats, although these can get very confusing if you are just starting out. I would recommend starting with wOBA for offense and DIPS for pitchers.

Here’s a great video about FIP (which is related to DIPS) from one of their writers to get you started. (His videos are a little different than mine, but probably better. I mean, he’s got dragons, I can’t compete with dragons.)


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